Variable-voltage transformer



April l, 1930. E J, ZELT 1,752,873

VARIABLE VOLTAGE TRANSFRHER Filed Oct. 17.. 1928 Patented Apr. 1, 1930 UNITED STATES PATENT OFFICE' ELMER J'. ZELT, OF FORT WAYNE, INDIANA, ASSIGNORTO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK VARIABLE-VOLTAGE TRANSFORMER Application led October 17, 1928. Serial No. 313,106.

My invention relates to variable voltage transformers and more particularly to transformers having switching devices for varying or adjusting their voltages. The invention is especially useful in connection with small transformers such as are often used to operate electrical toys. Such transformers are generally supplied with current from a constant -potential source but a secondary 1o voltage which may be varied or adjusted be.

tween certain limits is often desirable. The general object of the invention is to provide a transformer with an improved switching arrangement for varying, or adjusting its j voltage.

The invention will be better understood from the-following description taken in connection withthe accompanying drawing in which Fig. 1 is a perspective view of a transformer provided with a voltage adjusting switch constructed in accordance with the invention Fig. 2 is a side view, partly in section, .of the transformer shown in Fig. l; Figs. 3 and 4 are views of detailsA of con- '25 struction, andv Fig. 5 is a circuit diagram of the transformer windings and switch. Like reference characters indicate similar parts in the different figures of the drawing.

The invention will be explained in connection with a transformer 10 enclosed in a sheet metal casing 11 as shown in Figs. 1 and 2 of the drawing. A The transformer is provided with taps and tap leads extending to a tap switch mounted on one of the sidewalls 12 of the casing. switchlevei` 13 is mounted outside the wall 12 of the casing to turn on a pin 14 carried by a plate 15 of insulating material which is secured against the inner surface of the wall 12. The pin 14 passes l0 through a hole in the wall 12 somewhat larger than the pin so that the two do not touch. The wall 12 has an opening 16 under the path of the outer or contact making end of the lever 13 so that this end of the lever may be moved by a lmurled button 17 in a curved path along the outer surface of the plate 15. The transformer has two windings 18 and 19 as indicatedin Fig. 5'. The Winding 19 is divided into sections connected by tap leads 2Ol to xed contacts 21 heldin place by a 'from the scope of the invention as de tact with any one of the vcontacts 21 when vmoved over it.'

The winding 19, tap leads 20\and fixed contacts 21 are all formed from a single continuous conductor. After each section of this winding is formed, a loop is leftin the conductor before beginning the next section of the winding,tlie loops being long enough to form the tap leads 20 and xed contacts 21, the ends of the loops being bent around the contact support 22 to form the contacts 21 as shown most clearly in Fig. 4. The contact support has notches in its edges to receive the loops and maintain the contacts properly spaced. The insulation, if any, must be removed from the faces of the contacts which are exposed through the openings 25 1n the plate 15 so that good electrical connection may be made between the contacts and the lever 13. The pin 14 and one end of the winding 19 are connected to the two outside transformer leads 26. It will be obvious that the number of active turns in the winding 19 and therefore the voltageratio pf the transformer may be varied or adjusted byv changing the contact making osition of the lever 13. 'ljhe invention provi es a simpleand inexpensive construction and avoids the necessity for scribing and illustratinga preferred form thereof but it will be apparent that various changes may be made without departing ed in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is.:

1. A variable voltage transformer having a winding, a plurality of fixed contacts connected to said winding, an insulating plate, a switch member mounted on said plateand A movable along one of its faces and means at s the other face of said plate for sup orting said contacts in spaced relation, sai plate being perforated to ermit said switch member to move over sai contacts.

2. A variable voltage transformer having w a winding, a casing enclosing said transformer, an insulating plate secured to the inner surface of said casing, a movable switch member outside said casing, means mounted on said plate and extending through said casing l5 to support said switch member, means at the inner surface of said plate for supportinga lurality of fixed contacts, and connections J etween said contacts! and said Winding, said plate and casing having openings to permit 2@ said switch member to move over said con tacts.

3. A switch including an insulating support, a plurality of conductors surrounding said support at spaced intervals to form a 25 row of ed contacts, an insulating plate adjacent said support, said plate having openings spaced to correspond to the spacing of said contacts, sai'd contacts extending from their support throughvsaid openings, and a 3@ contact movable over said fixed contacts and along the face of said plate opposite said support.

In witness whereof, I have hereunto set my hand this th day of October, 1927.

ELMER J'. ZELT. 

